From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38A7CC55189 for ; Wed, 22 Apr 2020 12:06:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 167CC20780 for ; Wed, 22 Apr 2020 12:06:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="X5nJyTqx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728594AbgDVMGG (ORCPT ); Wed, 22 Apr 2020 08:06:06 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:49092 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726446AbgDVMGG (ORCPT ); Wed, 22 Apr 2020 08:06:06 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 03MC2rO5097413; Wed, 22 Apr 2020 12:05:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=corp-2020-01-29; bh=L7GWEspZEtRD1L/VpVBFE+u2DMBWTYytg1A5zTqZe30=; b=X5nJyTqxnfILH2uNAa7QDwqOe8hrE6bDeRIvPmz1Cpaoh53/11LPQPw4KtyysOCmdkPi HiB5s88TgJfH6kGG/vfz0meC7MjVbU8YZyJ13789MnTI2g+ypq4g7gXTMZFczjrg+7Q2 3HuFxt3gbvnbw6fC0WkPO27FuVleMvCSnpWPcSRaa/UDboA3z82Q8BpwquavPEnsNerG aD+PTW6qPezUpl01xWk3L3RK8W9Zzr+wj6Bhad/SDV8qjmPPjjj8cZbtzpAmLr5sYcA+ 0u25f+ExdHzlDGJVayFr2cB9giFclsvPfZx9K0suD3VjISH/tzfnTiPZvr1slurgZcII bA== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by aserp2120.oracle.com with ESMTP id 30fsgm2cbn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 22 Apr 2020 12:05:45 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 03MC2HqJ052051; Wed, 22 Apr 2020 12:03:44 GMT Received: from pps.reinject (localhost [127.0.0.1]) by userp3030.oracle.com with ESMTP id 30gb1jeep1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 22 Apr 2020 12:03:44 +0000 Received: from userp3030.oracle.com (userp3030.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 03MC3imt056174; Wed, 22 Apr 2020 12:03:44 GMT Received: from control-surface.uk.oracle.com (dhcp-10-175-178-214.vpn.oracle.com [10.175.178.214]) by userp3030.oracle.com with ESMTP id 30gb1jeehu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 22 Apr 2020 12:03:43 +0000 Received: from control-surface.uk.oracle.com (localhost [127.0.0.1]) by control-surface.uk.oracle.com (8.15.2/8.15.2) with ESMTPS id 03MC3epQ080674 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Wed, 22 Apr 2020 13:03:41 +0100 Received: (from jch@localhost) by control-surface.uk.oracle.com (8.15.2/8.15.2/Submit) id 03MC3dPx080672; Wed, 22 Apr 2020 13:03:39 +0100 X-Authentication-Warning: control-surface.uk.oracle.com: jch set sender to john.haxby@oracle.com using -f From: John Haxby To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Andi Kleen , Jonathan Corbet Cc: x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, John Haxby Subject: [PATCH 0/1] x86/fpu: Allow clearcpuid= to clear several bits Date: Wed, 22 Apr 2020 13:03:18 +0100 Message-Id: X-Mailer: git-send-email 2.25.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9598 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 clxscore=1015 spamscore=0 bulkscore=0 phishscore=0 suspectscore=0 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004220097 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Back in the mists of time, well, prior to 4.14.9, you could put clearcpuid=N several times on the command line to clear several CPUID bits. Unfortunately, there was a problem with the way that this was done which meant XSAVE, in particular, wasn't cleared early enough. This was fixed in 0c2a3913d6f5 ("x86/fpu: Parse clearcpuid= as early XSAVE argument"). Unfortunately that also meant that only one bit could be cleared. This patch mostly fixes that. Gone is the old, anachronistic, multiple clearcpuid= arguments to be replaced by a single clearcpuid=BITNUM[,BITNUM,...] argument. It's no longer possible to clear perhaps dozens of flags with a very long kernel command line, but you can clear up to about eight bits now instead of just one. jch John Haxby (1): x86/fpu: Allow clearcpuid= to clear several bits .../admin-guide/kernel-parameters.txt | 24 ++++++++++--------- arch/x86/kernel/fpu/init.c | 18 ++++++++------ 2 files changed, 24 insertions(+), 18 deletions(-) -- 2.25.3